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hugetlbpage.c

/*
 * SPARC64 Huge TLB page support.
 *
 * Copyright (C) 2002, 2003, 2006 David S. Miller (davem@davemloft.net)
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/sysctl.h>

#include <asm/mman.h>
#include <asm/pgalloc.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/cacheflush.h>
#include <asm/mmu_context.h>

/* Slightly simplified from the non-hugepage variant because by
 * definition we don't have to worry about any page coloring stuff
 */
#define VA_EXCLUDE_START (0x0000080000000000UL - (1UL << 32UL))
#define VA_EXCLUDE_END   (0xfffff80000000000UL + (1UL << 32UL))

static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *filp,
                                          unsigned long addr,
                                          unsigned long len,
                                          unsigned long pgoff,
                                          unsigned long flags)
{
      struct mm_struct *mm = current->mm;
      struct vm_area_struct * vma;
      unsigned long task_size = TASK_SIZE;
      unsigned long start_addr;

      if (test_thread_flag(TIF_32BIT))
            task_size = STACK_TOP32;
      if (unlikely(len >= VA_EXCLUDE_START))
            return -ENOMEM;

      if (len > mm->cached_hole_size) {
              start_addr = addr = mm->free_area_cache;
      } else {
              start_addr = addr = TASK_UNMAPPED_BASE;
              mm->cached_hole_size = 0;
      }

      task_size -= len;

full_search:
      addr = ALIGN(addr, HPAGE_SIZE);

      for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
            /* At this point:  (!vma || addr < vma->vm_end). */
            if (addr < VA_EXCLUDE_START &&
                (addr + len) >= VA_EXCLUDE_START) {
                  addr = VA_EXCLUDE_END;
                  vma = find_vma(mm, VA_EXCLUDE_END);
            }
            if (unlikely(task_size < addr)) {
                  if (start_addr != TASK_UNMAPPED_BASE) {
                        start_addr = addr = TASK_UNMAPPED_BASE;
                        mm->cached_hole_size = 0;
                        goto full_search;
                  }
                  return -ENOMEM;
            }
            if (likely(!vma || addr + len <= vma->vm_start)) {
                  /*
                   * Remember the place where we stopped the search:
                   */
                  mm->free_area_cache = addr + len;
                  return addr;
            }
            if (addr + mm->cached_hole_size < vma->vm_start)
                    mm->cached_hole_size = vma->vm_start - addr;

            addr = ALIGN(vma->vm_end, HPAGE_SIZE);
      }
}

static unsigned long
hugetlb_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
                          const unsigned long len,
                          const unsigned long pgoff,
                          const unsigned long flags)
{
      struct vm_area_struct *vma;
      struct mm_struct *mm = current->mm;
      unsigned long addr = addr0;

      /* This should only ever run for 32-bit processes.  */
      BUG_ON(!test_thread_flag(TIF_32BIT));

      /* check if free_area_cache is useful for us */
      if (len <= mm->cached_hole_size) {
              mm->cached_hole_size = 0;
            mm->free_area_cache = mm->mmap_base;
      }

      /* either no address requested or can't fit in requested address hole */
      addr = mm->free_area_cache & HPAGE_MASK;

      /* make sure it can fit in the remaining address space */
      if (likely(addr > len)) {
            vma = find_vma(mm, addr-len);
            if (!vma || addr <= vma->vm_start) {
                  /* remember the address as a hint for next time */
                  return (mm->free_area_cache = addr-len);
            }
      }

      if (unlikely(mm->mmap_base < len))
            goto bottomup;

      addr = (mm->mmap_base-len) & HPAGE_MASK;

      do {
            /*
             * Lookup failure means no vma is above this address,
             * else if new region fits below vma->vm_start,
             * return with success:
             */
            vma = find_vma(mm, addr);
            if (likely(!vma || addr+len <= vma->vm_start)) {
                  /* remember the address as a hint for next time */
                  return (mm->free_area_cache = addr);
            }

            /* remember the largest hole we saw so far */
            if (addr + mm->cached_hole_size < vma->vm_start)
                    mm->cached_hole_size = vma->vm_start - addr;

            /* try just below the current vma->vm_start */
            addr = (vma->vm_start-len) & HPAGE_MASK;
      } while (likely(len < vma->vm_start));

bottomup:
      /*
       * A failed mmap() very likely causes application failure,
       * so fall back to the bottom-up function here. This scenario
       * can happen with large stack limits and large mmap()
       * allocations.
       */
      mm->cached_hole_size = ~0UL;
      mm->free_area_cache = TASK_UNMAPPED_BASE;
      addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
      /*
       * Restore the topdown base:
       */
      mm->free_area_cache = mm->mmap_base;
      mm->cached_hole_size = ~0UL;

      return addr;
}

unsigned long
hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
            unsigned long len, unsigned long pgoff, unsigned long flags)
{
      struct mm_struct *mm = current->mm;
      struct vm_area_struct *vma;
      unsigned long task_size = TASK_SIZE;

      if (test_thread_flag(TIF_32BIT))
            task_size = STACK_TOP32;

      if (len & ~HPAGE_MASK)
            return -EINVAL;
      if (len > task_size)
            return -ENOMEM;

      if (flags & MAP_FIXED) {
            if (prepare_hugepage_range(addr, len))
                  return -EINVAL;
            return addr;
      }

      if (addr) {
            addr = ALIGN(addr, HPAGE_SIZE);
            vma = find_vma(mm, addr);
            if (task_size - len >= addr &&
                (!vma || addr + len <= vma->vm_start))
                  return addr;
      }
      if (mm->get_unmapped_area == arch_get_unmapped_area)
            return hugetlb_get_unmapped_area_bottomup(file, addr, len,
                        pgoff, flags);
      else
            return hugetlb_get_unmapped_area_topdown(file, addr, len,
                        pgoff, flags);
}

pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr)
{
      pgd_t *pgd;
      pud_t *pud;
      pmd_t *pmd;
      pte_t *pte = NULL;

      /* We must align the address, because our caller will run
       * set_huge_pte_at() on whatever we return, which writes out
       * all of the sub-ptes for the hugepage range.  So we have
       * to give it the first such sub-pte.
       */
      addr &= HPAGE_MASK;

      pgd = pgd_offset(mm, addr);
      pud = pud_alloc(mm, pgd, addr);
      if (pud) {
            pmd = pmd_alloc(mm, pud, addr);
            if (pmd)
                  pte = pte_alloc_map(mm, pmd, addr);
      }
      return pte;
}

pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
{
      pgd_t *pgd;
      pud_t *pud;
      pmd_t *pmd;
      pte_t *pte = NULL;

      addr &= HPAGE_MASK;

      pgd = pgd_offset(mm, addr);
      if (!pgd_none(*pgd)) {
            pud = pud_offset(pgd, addr);
            if (!pud_none(*pud)) {
                  pmd = pmd_offset(pud, addr);
                  if (!pmd_none(*pmd))
                        pte = pte_offset_map(pmd, addr);
            }
      }
      return pte;
}

int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
{
      return 0;
}

void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
                 pte_t *ptep, pte_t entry)
{
      int i;

      if (!pte_present(*ptep) && pte_present(entry))
            mm->context.huge_pte_count++;

      addr &= HPAGE_MASK;
      for (i = 0; i < (1 << HUGETLB_PAGE_ORDER); i++) {
            set_pte_at(mm, addr, ptep, entry);
            ptep++;
            addr += PAGE_SIZE;
            pte_val(entry) += PAGE_SIZE;
      }
}

pte_t huge_ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
                        pte_t *ptep)
{
      pte_t entry;
      int i;

      entry = *ptep;
      if (pte_present(entry))
            mm->context.huge_pte_count--;

      addr &= HPAGE_MASK;

      for (i = 0; i < (1 << HUGETLB_PAGE_ORDER); i++) {
            pte_clear(mm, addr, ptep);
            addr += PAGE_SIZE;
            ptep++;
      }

      return entry;
}

struct page *follow_huge_addr(struct mm_struct *mm,
                        unsigned long address, int write)
{
      return ERR_PTR(-EINVAL);
}

int pmd_huge(pmd_t pmd)
{
      return 0;
}

struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
                       pmd_t *pmd, int write)
{
      return NULL;
}

static void context_reload(void *__data)
{
      struct mm_struct *mm = __data;

      if (mm == current->mm)
            load_secondary_context(mm);
}

void hugetlb_prefault_arch_hook(struct mm_struct *mm)
{
      struct tsb_config *tp = &mm->context.tsb_block[MM_TSB_HUGE];

      if (likely(tp->tsb != NULL))
            return;

      tsb_grow(mm, MM_TSB_HUGE, 0);
      tsb_context_switch(mm);
      smp_tsb_sync(mm);

      /* On UltraSPARC-III+ and later, configure the second half of
       * the Data-TLB for huge pages.
       */
      if (tlb_type == cheetah_plus) {
            unsigned long ctx;

            spin_lock(&ctx_alloc_lock);
            ctx = mm->context.sparc64_ctx_val;
            ctx &= ~CTX_PGSZ_MASK;
            ctx |= CTX_PGSZ_BASE << CTX_PGSZ0_SHIFT;
            ctx |= CTX_PGSZ_HUGE << CTX_PGSZ1_SHIFT;

            if (ctx != mm->context.sparc64_ctx_val) {
                  /* When changing the page size fields, we
                   * must perform a context flush so that no
                   * stale entries match.  This flush must
                   * occur with the original context register
                   * settings.
                   */
                  do_flush_tlb_mm(mm);

                  /* Reload the context register of all processors
                   * also executing in this address space.
                   */
                  mm->context.sparc64_ctx_val = ctx;
                  on_each_cpu(context_reload, mm, 0, 0);
            }
            spin_unlock(&ctx_alloc_lock);
      }
}

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